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Thurs. Feb. 10, 2011 — Prenatal repair of spina bifida significantly reduced the risk of infant death or shunt placement compared with postnatal repair, according to results of a randomized clinical trial.

At 12 months, the prenatal surgery was associated with a 30 percent reduction in death or the need for a shunt compared with infants who had the surgery after they were born.

The actual rate of shunt placement was 40 percent in the prenatal group and 82 percent in the postnatal group, investigators in the multicenter trial reported online in the New England Journal of Medicine.

Moreover, infants who underwent surgery while in the womb also had significantly higher scores on tests of mental development and motor function at 30 months, the trial's second primary endpoint.

"The take-home lesson from this is in the actual rates of shunt placement to treat hydrocephalus," Dr. N. Scott Adzick, of the Children's Hospital of Philadelphia, said at a news briefing sponsored by the National Institute of Child Health and Human Development, which also sponsored the trial.

"As pediatric neurosurgeons have taught us, shunts are a mixed blessing. They treat the [build-up of fluid in the brain], but the bad news is that they are lifelong, and they frequently require revision to address shunt failure and infection."

Physicians responding by e-mail to a request for comments from MedPage Today and ABC News generally offered cautious assessments of the study's findings and potential implications.

"We all have been waiting for this study to be published," said Dr. Ian Holzman, of Mount Sinai School of Medicine in New York. "I think parents now should be given the option to have prenatal intervention."

But, he cautioned, "because there are maternal risks associated with this, it would never be considered the standard of care."

The 12- and 30-month results are not sufficient to predict the long-term outcome with prenatal surgery, according to Dr. Steven M. Donn, of the University of Michigan in Ann Arbor. The children will have to be followed for years before the true impact of the surgery can be assessed.

Donn, too, pointed out that the surgery "places the mother at significant risk for this and subsequent pregnancies, and it affects not only the study subjects, but could also affect their future siblings."

The surgery repairs or closes a condition called myelomeningocele, or the failure of the spine surrounding the spinal canal to close. It is the most common form of spina bifida, which, in turn, is the most common congenital anomaly of the central nervous system compatible with life.

Incidence of myelomeningocele has stabilized at a rate of about 3.4 per 10,000 live births since prenatal folic acid supplementation became the norm.

Myelomeningocele has an almost-universal association with Arnold-Chiari II malformation, which comprises a constellation of anomalies, hydrocephalus, and subsequent adverse effects on motor and cognitive function.

Prenatal ultrasonography has suggested that the ultimate neurologic deficit of the condition results from a combination of failed neural-tube formation and spinal cord injury related to prolonged exposure of neural elements to the intrauterine environment.

That observation led to the development of prenatal myelomeningocele repair via hysterotomy. First performed in 1997, the number of procedures had reached about 200 by 2003.

The current study was an effort to clarify the risks and benefits of prenatal myelomeningocele repair. Investigators at three maternal-fetal surgery centers conducted a randomized trial, which included securing agreement from other centers not to perform prenatal repair during the trial.

Enrollment began in February 2003 and continued through December 2010, when the trial ended early after an interim analysis showed a difference in efficacy.

Investigators enrolled 183 of the planned 200 women, 158 of whom were included in the 12-month analysis, 134 in the 30-month analysis.

Two perinatal deaths occurred in each group. Both deaths in the prenatal-surgery group occurred before shunt placement, and both deaths in the postnatal-surgery group occurred after shunt placement.

The difference in the rate of shunt placement translated into a 52 percent reduction in risk of shunt placement compared with post-natal surgery group.

"The lesson here is that the prenatal surgery group, on average, had much better motor function of the legs than the postnatal repair group," said Adzick.

Twice as many children in the prenatal-surgery group could walk independently at 30 months (42 percent versus 21 percent), even though the prenatal group had more severe lesions, he added.

"While this is a very promising and quite exciting result for this disease, not all the patients were helped, and there are significant risks. This procedure is not for everyone," co-investigator Dr. Diana Farmer, of the University of California San Francisco, said at the news briefing.

Dr. William Walsh, of Vanderbilt University in Nashville, Tenn., contacted by MedPage Today and ABC News, agreed, noting in an e-mail that the trial showed that prenatal surgery is a viable option, but not necessarily the standard of care for myelomeningocele.

The trial also resolved questions about prematurity and other risks posed by prenatal surgery, at least for the patients like those included in the study.

"I believe the trial, by randomizing the mothers answers that question," said Walsh. "The benefits outweigh the risks for the population selected: healthy women and fetuses at 19 to 25 weeks with no other defects."

The study was supported by the National Institute of Child Health and Human Development.

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